The present invention relates generally to sprayers and more particularly to aspiration-type sprayers for dispensing chemicals in a carrier fluid.
Aspiration-type sprayers are commonly used to dispense liquid-based chemicals, such as washing detergents, fertilizers, or pesticides. The chemical, which is generally provided in a container in concentrated form, is diluted and propelled by a carrier fluid. In a common arrangement, the carrier fluid is water, and the sprayer is coupled to a garden hose. Water from the hose enters the sprayer through an inlet and flows through an expansion or mixing chamber and out through an outlet. The expansion chamber is configured so that the flow of water creates a pressure drop (venturi effect), which draws the chemical from the container into the expansion chamber, where it mixes with the stream of water. The amount of chemical drawn into the stream of water varies with the amount of pressure drop generated within the expansion chamber and by the size of the passage into the expansion chamber through which the chemical is drawn.
One example of an aspiration-type sprayer is shown in U.S. Pat. No. 5,213,265 (the ""265 patent), issued to two of the inventors of the present invention, for a xe2x80x9cSingle Valve Aspiration Type Sprayerxe2x80x9d, and is incorporated herein by reference. The sprayer shown in the ""265 patent operates by the above-described principle, and includes a rotatable valve that sits in, and selectively opens and closes, both a carrier fluid passageway and a chemical aspiration passageway. The aspiration passageway connects the contents of the container with an expansion chamber. The sprayer of the ""265 patent provides for two modes of operationxe2x80x94xe2x80x9conxe2x80x9d (wherein the valve is positioned to open the carrier fluid passageway and the chemical aspiration passageway) and xe2x80x9coffxe2x80x9d (wherein the valve is positioned to close the carrier fluid passageway and the chemical aspiration passageway). This arrangement is quite suitable for spraying chemicals. However, it would be beneficial to provide for a mode of operation in which the carrier fluid could be sprayed with no (or only trace amounts) of the chemical mixed therewith.
U.S. Pat. No. 5,007,588, issued to Chow et al., for an xe2x80x9cAspiration-Type Sprayerxe2x80x9d shows another sprayer, which includes a nozzle that directs water to flow over an aspiration opening at the top of a passageway through which the contents of a connected container can be drawn. A bleed passage extends from the passageway below the aspiration opening. Opening and closing the bleed passage, as by the operator putting his finger thereover, permits the contents of the container to be selectively drawn through the passageway by the suction created by the flow of water over the aspiration opening. Although the sprayer disclosed in the Chow et al. patent can spray water without mixing the container contents therewith, a separate mechanism is required to control the flow of water through the sprayer, complicating operation of the sprayer. Further, the user must continuously, manually hold closed the bleed hole in order to aspirate the container contents.
U.S. Pat. No. 3,191,869, issued to Gilmour, for a xe2x80x9cSpraying Device Having Restricted Orifice and Expansion Chamber Constructionxe2x80x9d discloses another sprayer, which includes a valve mechanism for varying the amount of chemical drawn into a water stream. A passage is formed in an upper portion of the sprayer, connecting a mixing chamber with ambient environment. The passage is selectively restricted by a disk having a plurality of different-sized openings. The disk can be rotated to allow varying amounts of air to pass through the passage and into the mixing chamber, thereby varying the amount of chemical that is drawn into the water stream. Although the sprayer disclosed in the Gilmour patent permits a variable aspiration rate, a separate valve is required to control the flow of water through the sprayer, thus complicating the manufacture and operation of the sprayer.
Another method of varying the aspiration rate is disclosed in U.S. Pat. No. 4,901,923, issued to McRoskey, et al. for xe2x80x9cVariable Dilution Ratio Hose-End Aspirator Sprayer.xe2x80x9d In the sprayer of this patent, a passage between the container and the mixing chamber is selectively restricted by a disk having a plurality of different-sized openings. The disk can be rotated to vary the size of the orifice through which the chemical must pass to reach the mixing chamber. As with the sprayer of the Gilmour patent, however, a separate valve is required for controlling the flow of water through the sprayer.
Thus, there is a need in the art for an aspiration-type sprayer in which a single control valve can control the flow of carrier fluid and aspiration of chemical therein.
There is a further need in the art for an aspiration-type sprayer in which a single control valve can control the flow of carrier fluid and the mixing of varying quantities of chemical into the carrier fluid.
There is yet another need in the art for an aspiration-type sprayer which includes a mechanism for aspiration control without need for continuous, manual user action.
The present invention addresses the foregoing needs in the art by providing an aspiration type sprayer in which a bleed line, extending from a chemical supply tube, and a carrier channel can both be controlled by a single control valve.
According to one aspect of our invention an aspiration-type sprayer for use with a liquid chemical includes a sprayer head and a control valve assembly. The sprayer head includes (i) a carrier channel having an inlet for receiving a pressurized carrier fluid, an outlet through which the carrier fluid exits, and an expansion chamber in between the inlet and outlet, (ii) a chemical supply channel in flow communication with the expansion chamber of the carrier channel through an aspiration opening, so that a flow of carrier fluid through the carrier channel produces an aspiration flow from the chemical supply channel into the expansion chamber through the aspiration opening, the chemical supply channel having a free end for submersion in the liquid chemical, and (iii) a bleed line extending from the chemical supply channel between the aspiration opening and the liquid chemical, the bleed line connecting the chemical supply channel in flow communication to ambient air. The control valve assembly is seated in the sprayer head to simultaneously engage the carrier channel and the bleed line, the control valve assembly being movable relative to the sprayer head to (i) selectively open and close the carrier channel to selectively permit the carrier fluid to flow therethrough, and (ii) with the carrier channel open, selectively open and close the bleed line to selectively permit ambient air to be drawn into the chemical supply channel in response to the aspiration flow produced by the flow of carrier fluid.
According to another aspect of our invention, the bleed line is dimensioned so that, when pressurized carrier fluid is supplied to the inlet and the control valve assembly is positioned to open both the carrier channel and the bleed line, sufficient ambient air is drawn through the bleed line into the chemical supply channel so that no liquid chemical is drawn by the aspiration flow into the expansion chamber.
According to still another aspect of our invention, the bleed line is dimensioned so that, when pressurized carrier fluid is supplied to the inlet and the control valve assembly is positioned to open both the carrier channel and the bleed line, ambient air is drawn through the bleed line into the chemical supply channel at a flow rate sufficient to partially counterbalance the aspiration flow, so that liquid chemical is drawn into the expansion chamber in smaller proportions than when carrier fluid is supplied to the inlet and the control valve is positioned to open the carrier channel and close the bleed line.
In yet another aspect of our invention, the liquid chemical comprises two batches of liquid chemical, the chemical supply channel comprises (i) a first chemical passage in flow communication with the expansion chamber and having a free end for submersion in one of the batches of liquid chemical and (ii) a second chemical passage in flow communication with the expansion chamber and having a free end for submersion in the other of the batches of liquid chemical, the bleed line comprises a first bleed passage and a second bleed passage, each of the bleed passages connecting a corresponding one of the chemical passages in flow communication with ambient air, and the control valve assembly, with the carrier channel open, selectively opens and closes each of the bleed passages.
These and other objects, features, and advantages of the present invention will be more evident from the following description and drawings in which like reference numerals relate like elements throughout.